feat(gamification): list_recent_completions_cmd Tauri wrapper

Thin wrapper over kon_storage::list_recent_completions, parameterised
by day count. Serialises to camelCase JSON (day, count).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src-tauri/src/commands/tasks.rs

@@ -11,10 +11,11 @@ use kon_storage::{
     complete_subtask_and_check_parent as db_complete_subtask, complete_task as db_complete_task,
     delete_task as db_delete_task, get_task_by_id as db_get_task,
     insert_subtask as db_insert_subtask, insert_task as db_insert_task,
-    list_feedback_examples as db_list_feedback_examples, list_subtasks as db_list_subtasks,
+    list_feedback_examples as db_list_feedback_examples,
+    list_recent_completions as db_list_recent_completions, list_subtasks as db_list_subtasks,
     list_tasks as db_list_tasks, set_task_energy as db_set_task_energy,
-    uncomplete_task as db_uncomplete_task, update_task as db_update_task, FeedbackRow,
+    uncomplete_task as db_uncomplete_task, update_task as db_update_task, DailyCompletionCount,
-    FeedbackTargetType, TaskRow,
+    FeedbackRow, FeedbackTargetType, TaskRow,
 };
 
 use crate::AppState;
@@ -386,3 +387,16 @@ pub async fn complete_subtask_cmd(
         .await
         .map_err(|e| e.to_string())
 }
+
+/// Phase 8: daily completion counts for the Tasks-page badge and the
+/// 7-day momentum sparkline. Returns a fixed-length oldest-first
+/// series. Empty days are explicit zeros.
+#[tauri::command]
+pub async fn list_recent_completions_cmd(
+    state: tauri::State<'_, AppState>,
+    days: u32,
+) -> Result<Vec<DailyCompletionCount>, String> {
+    db_list_recent_completions(&state.db, days)
+        .await
+        .map_err(|e| e.to_string())
+}

src-tauri/src/lib.rs

@@ -317,6 +317,7 @@ pub fn run() {
             commands::tasks::extract_tasks_from_transcript_cmd,
             commands::tasks::list_subtasks_cmd,
             commands::tasks::complete_subtask_cmd,
+            commands::tasks::list_recent_completions_cmd,
             // HITL feedback (Phase 2 roadmap)
             commands::feedback::record_feedback,
             commands::feedback::list_feedback_examples_cmd,